VW TDI clutch question

So I have a chance to buy an 04 TDI for cheap. The car is in good shape but makes a loud clacking noise. The shop told the owner that it needs a clutch and flywheel. Aparently the dual mass flywheel has failed.

Does anyone have experience with these? Does the diagnosis sound right?

Any words of caution?

How hard is it to change the clutch, do I need any special tools?

What exactly is a dual mass flywheel? Does it have spring loaded balance weights?

Can I use an aftermarket standard flywheel and clutch? Are they any good?

I am thinking it would be a good ecenomical car for my son at university. Thanks for any and all advice!

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